Hi, I just got back from the lake and when I went to take out the drain plug in the center of my boat noticed that it was a brown milky color. There was quite a bit of it in the bilge area and around the center ballast. I checked the trans oil dip stick and it was all brownish white. Does anyone know what would cause this?
We ran the boat all day, did not notice anything unusual, and it has 310 hours on it. I just had the impeller changed, could this problem be related to it? Any help would be greatly appreciated.

Yes the fluid level is fine. It happened towards the end of the day. At one point earlier I had looked in the bilge area and the water was clear (small amount) when we pulled the boat was when I noticed it. Boat is always garaged, we live in N.CA so not too cold in the winter. I have read some on the transmission cooler, what is this and where is it located? Thanks!

I just looked again at the dipstick. It is pretty high up on the stick. There are two notches at the bottom of the stick and the white stuff goes up about another inch or two from that. I am guessing that it too full. If this is a seal is it a big repair? thanks!

I am not sure what engine (LTR?) you have, but there are likely two thick walled, approx 3/4 inch in diameter, black hoses coming from the transmission to a metal tube that is in the fresh water intake circuit. A large diameter water line will then be going in and out of this large tube. This tube is your transmission cooler. it is nothing but a mini radiator and if it has rotted on the inside, it is pushing water into your transmission instead of just cooling the circulating oil. The fluid level in the transmission therefore rises and begins to leak out the vent into your bilge.

Make sure to change the transmission oil ASAP. I would change, drain, and change again. Then replace the transmission cooler (SkiDim perhaps?). Again, yours may be different. Your manual may show the transmission cooler, as the strainer which MC recommend you clean before each outing (which I believe almost no one does) is located at the bottom of the transmission cooler.

Thanks Vision,
I am not sure about the engine size, the boat is a 2002 X Star, it says Vortec on the engine. It looks like a Chevy engine, 8 cylinder. I looked around but did not see the cannister/cooler that you mentioned. Is it on the side or in back? It looks like the white stuff is coming from the front of the enigine (where the tranny is) right behind the rear seat. I do see large hoses that are there, but not sure where the cooler is. Assuming that the problem it is the cooler, is that a big repair? Do they have to pull the engine to replace it? Thanks

Thanks Vision,
I am not sure about the engine size, the boat is a 2002 X Star, it says Vortec on the engine. It looks like a Chevy engine, 8 cylinder. I looked around but did not see the cannister/cooler that you mentioned. Is it on the side or in back? It looks like the white stuff is coming from the front of the enigine (where the tranny is) right behind the rear seat. I do see large hoses that are there, but not sure where the cooler is. Assuming that the problem it is the cooler, is that a big repair? Do they have to pull the engine to replace it? Thanks

No, it is reasonably simple to replace on most models. Follow the cooling hoses from your transmission. On the 5.7 Indmar motors which is likely what you have, they should terminate in a heat exchanger about the size of small beer can on the starboard side of the motor. But it does vary with engine model.

Go ahead and drain and replace the transmission oil so that the water does not sit in the transmission.

Thanks for the pic. I will drain the fluid ASAP, I was worried about that, the water sitting in it over a time and then potentially rusting the parts. The Mastercraft dealer can't get me in for two weeks so I better do this quickly. I also noticed that there is a suction sound when I remove the dipstick. This seemed ususal to me also. I will start with the cooler, is there also a screen or filter of some sort that I have to clean?

Thanks for the pic. I will drain the fluid ASAP, I was worried about that, the water sitting in it over a time and then potentially rusting the parts. The Mastercraft dealer can't get me in for two weeks so I better do this quickly. I also noticed that there is a suction sound when I remove the dipstick. This seemed ususal to me also. I will start with the cooler, is there also a screen or filter of some sort that I have to clean?

Yes, at the bottom of the transmission cooler/heat exchanger, if you remove the water hose and reach in there is a screen to trap debris. Good to check every few outings.